The present invention relates to a light source unit for use in a vehicular lamp.
Conventionally, a so-called projection-type vehicular lamp implemented as a headlamp has been known.
In a projection-type vehicular lamp, light emitted by a light source disposed on the optical axis of the lamp is collected and reflected forward in the direction of the optical axis by a reflector, and the reflected light is radiated in the forward direction of the lighting unit through a projection lens mounted in front of the reflector.
By employing such a projection-type vehicular lamp it is possible to reduce the overall size of the lighting unit compared with a so-called parabolic-type vehicular lamp.
However, in the conventional projection-type vehicular lamp where a discharge light-emitting section of a discharge bulb or a filament of a halogen bulb is used for a light source thereof, the following problem occurs.
More specifically, because the actual light-emitting portion of the light source has a certain finite size, in order to appropriately reflect and control the light emitted by the light source it is necessary to provide a relatively large reflector. Moreover, it is necessary to provide a space for mounting and supporting the discharge or halogen bulb on the reflector, which further contributes to the need for a relatively large reflector. Also, the light source generates considerable heat, and the influence of the heat must be taken into consideration in the design of the reflector.
From the foregoing, there is a problem that a significant reduction in the size of the lighting unit cannot be obtained with the conventional projection-type vehicular lamp.
JP-A-2002-50214, JP-A-2001-332104 and JP-A-9-330604 disclose a vehicular lamp using an LED, which is a small-sized light source. Moreover, JP-A-2002-42520 and JP-A-2000-77689 teach a light-emitting device having a reflecting surface provided close to an LED. These references do not, however, teach a light source suitable for use in a vehicular headlamp or the like.